John F. McDyer

T Cell Responses to Mycobacterial Catalase-Peroxidase Profile a Pathogenic Antigen in Systemic Sarcoidosis

Sarcoidosis is a systemic granulomatous disease associated with local epithelioid granulomas, CD4+ T cells, and Th1 cytokines. The tissue Ags that drive this granulomatous inflammation are uncertain. In this study, we used IFN-γ-ELISPOT assays and flow cytometry to assess lung and blood T cell responses to the candidate pathogenic Ag, Mycobacterium tuberculosis catalase-peroxidase (mKatG) in patients with sarcoidosis from two centers. Despite differences in patient phenotypic, genetic, and prognostic characteristics, we report that T cell responses to mKatG were remarkably similar in these cohorts, with higher frequencies of mKatG-reactive, IFN-γ-expressing T cells in the blood of sarcoidosis patients compared with nontuberculosis sensitized healthy controls, and (in a subset) in greater numbers than T cells reactive to purified protein derivative. In sarcoidosis, mKatG-reactive CD4+ Th1 cells preferentially accumulated in the lung, indicating a compartmentalized response. Patients with or without Löfgren syndrome had similar frequencies of mKatG specific IFN-γ-expressing blood T cells. Circulating mKatG-reactive T cells were found in chronic active sarcoidosis but not in patients with inactive disease. Together, these results demonstrate that T cell responses to mKatG in sarcoidosis fit a profile expected for a pathogenic Ag, supporting an immunotherapeutic approach to this disease.

Primary Cytomegalovirus Phosphoprotein 65–Specific CD8+ T-Cell Responses and T-bet Levels Predict Immune Control During Early Chronic Infection in Lung Transplant Recipients

BACKGROUNDnCytomegalovirus (CMV) remains an important pathogen in solid organ transplantation, particularly lung transplantation. Lung transplant recipients (LTRs) mismatched for CMV (donor positive/recipient negative [D(+)R(-)]) are at highest risk for active CMV infection and have increased mortality. However, the correlates of immune control during chronic CMV infection remain incompletely understood.nnnMETHODSnWe prospectively studied 22 D(+)R(-) LTRs during primary CMV infection and into chronic infection. Immune responses during primary infection were analyzed for association with viral relapse during early chronic infection.nnnRESULTSnPrimary CMV infection was characterized by a striking induction of T-box transcription factor (T-bet) in CD8(+) T cells. CMV-specific effector CD8(+) T cells were found to be T-bet(+). After primary infection, 7 LTRs lacked immune control with relapsing viremia during early chronic infection. LTRs with relapsing viremia had poor induction of T-bet and low frequencies of phosphoprotein 65 (pp65)-specific CD8(+) effector T cells during primary infection. However, frequencies of IE1-specific CD8(+) effector T cells during primary infection were not associated with early relapsing viremia.nnnCONCLUSIONSnT-bet plays an important role in coordinating CD8(+) effector responses to CMV during primary infection. Moreover, CD8(+) T-bet induction and pp65-specific CD8(+) effector responses at the time of primary infection are important predictors of immune control of CMV during early chronic infection.

CD154 blockade abrogates allospecific responses and enhances CD4 + regulatory T-cells in mouse orthotopic lung transplant

Acute cellular rejection (ACR) is a common and important clinical complication following lung transplantation. While there is a clinical need for the development of novel therapies to prevent ACR, the regulation of allospecific effector T‐cells in this process remains incompletely understood. Using the MHC‐mismatched mouse orthotopic lung transplant model, we investigated the short‐term role of anti‐CD154 mAb therapy alone on allograft pathology and alloimmune T‐cell effector responses. Untreated C57BL/6 recipients of BALB/c left lung allografts had high‐grade rejection and diminished CD4+: CD8+ graft ratios, marked by predominantly CD8+>CD4+ IFN‐γ+ allospecific effector responses at day 10, compared to isograft controls. Anti‐CD154 mAb therapy strikingly abrogated both CD8+ and CD4+ alloeffector responses and significantly increased lung allograft CD4+: CD8+ ratios. Examination of graft CD4+ T‐cells revealed significantly increased frequencies of CD4+CD25+Foxp3+ regulatory T‐cells in the lung allografts of anti‐CD154‐treated mice and was associated with significant attenuation of ACR compared to untreated controls. Together, these data show that CD154/CD40 costimulation blockade alone is sufficient to abrogate allospecific effector T‐cell responses and significantly shifts the lung allograft toward an environment predominated by CD4+ T regulatory cells in association with an attenuation of ACR.

CD154 deficiency uncouples allograft CD8+ T-cell effector function from proliferation and inhibits murine airway obliteration.

Obliterative bronchiolitis (OB) limits the long‐term success of lung transplantation, while T‐cell effector mechanisms in this process remain incompletely understood. Using the murine heterotopic tracheal transplant model of obliterative airway disease (OAD) to characterize airway allograft rejection, we previously reported an important role for CD8+ T cells in OAD. Herein, we studied the role of CD154/CD40 costimulation in the regulation of allospecific CD8+ T cells, as airway rejection has been reported to be CD154‐dependent. Airway allografts from CD154−/− recipients had significantly lower day 28 OAD scores compared to wild‐type (WT) recipients, and adoptive transfer of CD8+ T cells from WT recipients, but not CD154−/− recipients, were capable of airway rejection in fresh CD154−/− allograft recipients. Intragraft CD8+ T cells from CD154−/− mice showed similar expression of the surface markers CD69, CD62Llow CD44high and PD‐1, but markedly impaired IFN‐γ and TNF‐α secretion and granzyme B expression versus WT controls. Unexpectedly, intragraft and systemic CD8+ T cells from CD154−/− recipients demonstrated robust in vivo expansion similar to WT recipients, consistent with an uncoupling of proliferation from effector function. Together, these data suggest that a lack of CD154/CD40 costimulation results in ineffective allospecific priming of CD8+ T cells required for murine OAD.

High-Quality CMV-Specific CD4+Memory Is Enriched in the Lung Allograft and Is Associated With Mucosal Viral Control: Lung CD4+Memory Contributes to Mucosal CMV Control

The maintenance of CMV‐specific T cell memory in lung transplant recipients (LTRs) is critical for host defense and allograft durability, particularly in donor+/recipient− (D+R−) individuals who demonstrate increased mortality. We studied CD4+ and CD8+ CMV‐specific memory responses to phosphoprotein 65 (pp65) in a prospective cohort of 18 D+R− LTRs, from bronchoalveolar lavage (BAL)‐obtained lung mononuclear cells (LMNC) and PBMC. Unexpectedly, pp65‐specific CD4+ and CD8+ IFN‐γ memory responses from LMNC were similar, in contrast to persistent CD8+ predominance in PBMC. Unlike the pulmonary CD8+ predominance during acute primary infection, compartmental equalization occurred in the CMV‐specific CD8+ memory pool during chronic infection, whereas CMV‐specific CD4+ memory was enriched in the bronchoalveolar space. Moreover, CMV‐specific CD4+ memory T cells with multifunctional production of IFN‐γ, TNF‐α, IL‐2 and MIP‐1β were significantly increased in LMNCs, in contrast to similar intercompartmental CD8+ memory function. Moreover, the absolute number of CMV‐specific CD4+IFN‐γ+ memory cells in BAL was significantly increased in LTRs exhibiting viral control compared to those with CMV early antigen positivity. Collectively, these data demonstrate both preferential distribution and functional quality of CMV‐specific CD4+ memory in the lung allograft during chronic infection, and show an important association with CMV mucosal immunity and viral control.